Optical coherence tomography (OCT) has been viewed as an “optical analogy” of ultrasound sonogram (US) imaging since its invention in early 1990's. Compared to the conventional image-guided interventions (IGI) using modalities such as magnetic resonance imaging (MRI), X-ray computed tomography (CT) and ultrasound (US), OCT has much higher spatial resolution and therefore possesses great potential for applications in a wide range of microsurgeries, such as vitreo-retinal surgery, neurological surgery, otolaryngologic surgery and cochlear implantation. It has recently been demonstrated that OCT can be highly effective in freehand or robotically assisted retinal imaging or cochlear implantation, for example. A single-mode fiber can be lensed with state-of-the-art micro-optics to form a light beam with a spot size around 11 μm to 18 μm in retinal imaging, gastrointestinal endoscopy, coronary artery imaging, and needle-based Doppler OCT. Thus, OCT fiber optic sensing and imaging are becoming powerful tools for non-destructive cross-sectional imaging of biological tissues.
Retinal surgery is one example of microsurgery. In current practice, retinal surgery is performed under an operating microscope with free-hand instrumentation. Human limitations include an inability to clearly view surgical targets, physiological hand tremor, and lack of tactile feedback in tool-to-tissue interactions. In addition, tool limitations, such as lack of proximity sensing or smart functions, are important factors that contribute to surgical risk and reduce the likelihood of achieving surgical goals. Current instruments do not provide physiological or even basic interpretive information. Surgical outcomes (both success and failure) are limited, in part, by technical hurdles that cannot be overcome by conventional instrumentation.
Surgical blades are one type of hand-held surgical instrument. A hand-held instrument has the following advantages. First, it is small and lightweight, making it easy to access tight spaces. Second, surgeons are intimately familiar with hand-held instruments which can leverage the surgeons' experience and skills with little training Third, a small hand-held instrument offers greater safety because the surgeon can more easily override or remove the instrument in cases of malfunction.
A hand-held instrument, however, poses additional challenges over mechanically-rigid instruments. An operator of the hand-held instrument may be require control a tool tip of the instrument within very small tolerances, including sub-millimeter scale. For example, in some applications, surgical blades may need to be controlled at the sub-millimeter or micron scale. A surgeon may be required to perform a cut with a surgical blade that achieves a high level of accuracy with regard to the depth of the cut or it may be desirable to perform a cut that has a substantially even depth across a length of the cut. However, hand tremor, or physiological motion (e.g., the breathing and/or heartbeat, as well as volitional movement of the surgeon and/or patient) can make accurate and/controlled cuts or other micro-manipulations difficult to achieve and may cause damage to surrounding delicate tissues or cause localized hemorrhage or other injury and pose a high risk to the safety of the patient during performance of the procedure. The resulting involuntary changes in relative distance between the blade or other tool tip and the surgical tissue surface, although usually on the order of a few hundreds of micrometer at less than 5 Hz, may cause serious error due to the scale of microsurgery. Currently, no hand held surgical blade system can satisfy all of the above challenges during performance of a cutting operation. There remains a need for improved micro-manipulation systems and methods for surgical or microsurgical applications.